Papers by Hartmut Fischer
Crystal Growth & Design
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Crystal Growth & Design
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Smart Polymers and their Applications, 2019
Abstract After millions of years of evolution, nature has developed materials and systems based o... more Abstract After millions of years of evolution, nature has developed materials and systems based on the concept of damage management (healing) to extend survival possibilities. In the last 20 years, the dream of implementing this concept to engineering systems to extend service lifetime has become a reality. The field of self-healing engineering materials is growing exponentially, both in the number of research groups involved as well as the number of concepts explored, although finding applications for many of these new concepts is not straightforward. In this chapter, we focus on analyzing the main mechanisms and concepts developed in the field of self-healing polymers and introduce some explored applications of healable polymers, all from the point of view of understanding the concept of healing as the restoration of lost functionalities.
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ACS Applied Polymer Materials, 2021
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Advanced Materials Letters, Dec 1, 2018
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Crystal Growth & Design, 2019
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Active Protective Coatings, 2016
There is an ever growing demand for new developments and innovation in material systems, focusing... more There is an ever growing demand for new developments and innovation in material systems, focusing on energy and material saving and increased reliability and durability while applying new and modern technologies. This happens especially in areas of more traditional and conservative use of materials like constructions, buildings etc. but also in high technology areas. Protection of materials and systems by coatings is one way to decrease maintenance and increase life-time expectations. As an alternative to the traditionally used passive protective coating systems, new concepts introduce the idea of active protective coatings. These technologies show not only a great potential to increase the lifetime of structures but also, and at same level of importance, to decrease maintenance costs. Existing active protective, sensing and self-healing approaches applied or likely to be applied to the field of organic coatings will be discussed in this chapter analyzing the pros and cons of each mechanism.
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Journal of Applied Polymer Science, 2017
ABSTRACTA facile two‐step process is developed to obtain polyester urethanes that contain various... more ABSTRACTA facile two‐step process is developed to obtain polyester urethanes that contain various concentrations of thermoreversible Diels–Alder adduct–based bonds for the development of adhesives. Besides linear systems thermoreversible networks have been included in the study. The reactions are verified using IR‐spectroscopy and gel permeation chromatography analysis. The material properties are characterized with solvent exposure tests, dynamic scanning calorimetry, microindentation and rheology and the potential for application as adhesives is tested with an elcometer. Material properties have been found highly tunable for the system, and high adhesive strengths (off‐scale) are found for polyester urethanes that are doped with an intermediate level Diels–Alder functional groups. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44972.
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Smart Materials and Structures, Jul 14, 2016
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Progress in Organic Coatings, Oct 1, 2017
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Materials and Corrosion-werkstoffe Und Korrosion, Oct 8, 2015
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Polymer, Nov 1, 2015
Epoxy resins are functionalized with Diels-Alder based thermo-reversible crosslinks to enable the... more Epoxy resins are functionalized with Diels-Alder based thermo-reversible crosslinks to enable the fabrication of composites that are capable of multiple self-healing-repair processes. The key challenge in realizing a structural combination of conventional epoxy amine systems with furfuryl and maleimide functional groups is to achieve a high conversion in the reversible cross-linked polymer network formation while avoiding the major side-reactions. We have developed a two-step process consisting of a bulk prepolymerization reaction followed by a network formation step. The second step is performed in an extruder to realize a good mixing at high temperatures, while keeping the residence time at that temperature short to avoid maleimide side-reactions. The obtained oligomers are characterized using NIR, NMR, DSC, GPC analyses while solvent exposure tests and rheological measurements are performed to prove the formation of a thermo-reversible network and study their behavior in relation to the cross-linker concentration. Densely cross-linked, solvent resistant polymeric networks are obtained that maintain the ability to un-crosslink and thus regaining fluid behavior at elevated temperatures for at least five subsequent heat cycles. Glass fiber reinforced polymer composite films, which are fabricated using these resins, demonstrate that the thermo-reversible effect is strong enough to achieve full self-healing of a severely cracked and delaminated test specimen.
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Materials today communications, Sep 1, 2016
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Secondary resources containing (catcium) atuminium-silicate phases, e.g., fly ash, slag or bottom... more Secondary resources containing (catcium) atuminium-silicate phases, e.g., fly ash, slag or bottom ash are used as precursor for binders such as geopolymers. Because secondary resources can be highly variable in terms of their potential to dissolve and form reaction products, analytical methods are needed to evaluate their potential as a precursor and to optimize the geopolymer mix design. The most commonly used methods (e.g., XRF, XRD) for measuring the characteristics of source materials which influence binder performance, do not capture heterogeneity of the particles and do not necessarily reveal the key parameter that is most dominant for the binder performance. This presentation therefore discusses the applicability of several techniques we have investigated to capture inter- and intra-particle variations of aluminium-silicates and to evaluate the potential influence of these variations on geopolymer performance. The evaluated techniques are: automated phase mapping based on EDS spectral imaging and processing using principal component analysis; feature sizing and chemical typing (fSC semi-quantitative fTIR 29 and solid state Si NMR.
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Renewable Energy, 2019
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Recent Advances in Polymer Nanocomposites
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Papers by Hartmut Fischer